JP2018047850A - Tire pressure monitoring system, monitoring device and detection device - Google Patents

Abstract

Provided is a tire pressure monitoring system that enables a monitoring device and a detection device to perform two-way communication without adjusting a rotation angle of a tire when the vehicle is stopped, and that can reduce power consumption of the detection device. . Kind Code: A1 A tire pressure monitoring system is provided in a vehicle, which detects a pressure of a tire and wirelessly transmits a pressure signal obtained by detecting a pressure of the tire, and receives a pressure signal to monitor a pressure of each tire. And a monitoring device 1 that performs the monitoring. The monitoring device 1 includes an angle information obtaining unit that obtains angle information indicating a rotation angle of the tire 3, and a request for wirelessly transmitting a request signal for requesting air pressure information to the detection device 2 with a signal strength corresponding to the obtained angle information. A signal transmitting unit. The detecting device 2 includes a pneumatic signal transmitting unit that transmits pneumatic information when receiving the request signal transmitted from the monitoring device 1. [Selection diagram] Fig. 1

Description

  The present invention relates to a tire pressure monitoring system, and a monitoring device and a detection device constituting the tire pressure monitoring system.

  There is a tire pressure monitoring system (TPMS: Tire Pressure Monitoring System) that detects the air pressure of a tire provided in a vehicle and issues a warning to a user when the detected air pressure is abnormal. The tire pressure monitoring system includes a detection device provided for each tire and a monitoring device disposed on the vehicle body. The detection device detects the air pressure of the tire and wirelessly transmits the air pressure signal obtained by the detection using radio waves in the UHF band. The monitoring device receives the air pressure signal transmitted from each detection device, and monitors the air pressure of each tire based on the received air pressure signal. When there is an abnormality in the tire air pressure, the monitoring device displays a warning on the tire air pressure abnormality and issues a warning.

There are two types of communication methods in the tire pressure monitoring system: a unidirectional method in which the detection device spontaneously transmits an air pressure signal, and a bidirectional method in which the detection device transmits an air pressure signal in response to a request from the monitoring device. is there. When the vehicle is stopped, the bidirectional method is suitable.
Since the detection device is driven by a battery, the reception sensitivity of the request signal and the strength of the air pressure signal are set as small as possible in order to reduce power consumption. Also in the monitoring device, it is desirable to reduce the power consumption by setting the signal strength of the request signal and the reception sensitivity of the air pressure signal low. Then, a rotation angle range in which the request signal does not reach the detection device is generated depending on the positional relationship between the monitoring device and the detection device when the vehicle is stopped, that is, the rotation angle of the tire. Similarly, a range of rotational angles occurs where the air pressure signal does not reach the monitoring device.

  Patent Document 1 discloses a technique for detecting a rotational position of a tire and guiding the vehicle to a stop position where the rotational position does not hinder communication between the monitoring device and the detection device.

Japanese Patent Laying-Open No. 2015-20482

  However, in Patent Document 1, the user has to move the vehicle according to the guidance and adjust the rotation angle of the tire, and there is a problem that the tire air pressure cannot be detected while the vehicle is completely stopped. It was.

  An object of the present invention is to provide a tire pressure monitoring system in which the monitoring device and the detection device can perform two-way communication without adjusting the rotation angle of the tire when the vehicle is stopped, and the power consumption of the detection device can be suppressed. It is to provide a monitoring device and a detection device.

  The tire pressure monitoring system according to this aspect is provided in a tire of a vehicle, and a detection device that wirelessly transmits a pressure signal obtained by detecting the pressure of the tire, and the pressure signal transmitted from the detection device. A tire pressure monitoring system comprising: a monitoring device that receives and monitors the tire air pressure, wherein the monitoring device acquires angle information indicating a rotation angle of the tire; and the acquisition unit acquires the angle information A request signal transmission unit that wirelessly transmits a request signal for requesting the air pressure signal to the detection device with a signal intensity corresponding to the angle information, and the detection device receives the request signal transmitted from the monitoring device. A request signal receiving unit for receiving, and a pneumatic signal transmitting unit for transmitting the pneumatic signal when the request signal is received by the request signal receiving unit.

  The monitoring device according to this aspect is provided in a tire of a vehicle, receives the air pressure signal transmitted from a detection device that wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire, and receives the air pressure of the tire And a request signal for requesting the air pressure signal at a signal intensity corresponding to the angle information acquired by the acquisition unit. A request signal transmission unit that wirelessly transmits to the detection device.

  The detection device according to this aspect is a detection device that is provided in a tire of a vehicle and wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire, the request signal requesting the air pressure signal and the tire A request signal receiving unit that receives setting information for setting the signal strength of the air pressure signal in accordance with the rotation angle of the air pressure signal, and when the request signal and the setting information are received by the request signal receiving unit, the setting information And an air pressure signal transmitting unit for transmitting the air pressure signal with a signal intensity corresponding to the air pressure.

  Note that the present application can be realized not only as a tire pressure monitoring system, a monitoring device, and a detection device having such a characteristic configuration, but also as a tire pressure monitoring method using such characteristic processing as a step. The program can be realized as a program for causing a computer to execute such steps. Further, it may be realized as a semiconductor integrated circuit that realizes part or all of the tire pressure monitoring system, monitoring device or detection device, or may be realized as another system including the tire pressure monitoring system, monitoring device or detection device. it can.

  According to the above, a tire pressure monitoring system in which the monitoring device and the detection device can perform two-way communication without adjusting the rotation angle of the tire when the vehicle is stopped, and the power consumption of the detection device can be suppressed, A monitoring device and a detection device can be provided.

It is a conceptual diagram which shows the example of 1 structure of the tire pressure monitoring system which concerns on embodiment of this invention. It is a block diagram which shows one structural example of the monitoring apparatus. It is a conceptual diagram which shows an example of an identifier table. It is a conceptual diagram which shows LF dead zone. It is a conceptual diagram which shows an example of LF dead zone table. It is a conceptual diagram which shows an example of RF dead zone table. It is a block diagram which shows the example of 1 structure of a detection apparatus. It is a flowchart which shows the process sequence of a monitoring apparatus. It is a flowchart which shows the process sequence of a detection apparatus.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described. Moreover, you may combine arbitrarily at least one part of embodiment described below.

(1) A tire air pressure monitoring system according to this aspect is provided in a tire of a vehicle, and a detection device that wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire, and the above-mentioned transmitted from the detection device A tire pressure monitoring system comprising a monitoring device that receives a pneumatic pressure signal and monitors the tire pressure, wherein the monitoring device acquires angle information indicating a rotation angle of the tire, and the acquisition unit A request signal transmission unit that wirelessly transmits a request signal for requesting the air pressure signal to the detection device with a signal intensity corresponding to the angle information acquired in step, the detection device transmitted from the monitoring device A request signal receiving unit that receives the request signal; and a pneumatic signal transmission unit that transmits the pneumatic signal when the request signal is received by the request signal receiving unit.

In this aspect, the monitoring device transmits a request signal to the detection device with a signal intensity corresponding to the rotation angle of the tire, and the detection device transmits an air pressure signal to the detection device according to the request signal. The positional relationship between the monitoring device and the detection device changes depending on the rotation angle of the tire when the vehicle is stopped, and the intensity of the request signal that reaches the detection device also changes. When the detection sensitivity of the request signal in the detection device is low, it becomes difficult to receive the request signal depending on the rotation angle of the tire.
However, since the monitoring device can change the signal strength of the request signal according to the rotation angle of the tire, the detection device can receive a request signal having a certain strength or higher regardless of the rotation angle of the tire. Become. Therefore, the request signal can be received without setting the reception sensitivity of the request signal in the detection device high, and the power consumption in the detection device can be suppressed.

(2) The monitoring device determines a rotation angle range in which the intensity of the request signal reaching the detection device is increased according to a rotation angle of the tire, and a rotation angle range in which the intensity of the request signal is decreased, and Based on the request signal setting information storage unit that stores information for setting the signal strength of the request signal, the angle information acquired by the acquisition unit, and the information stored in the request signal setting information storage unit, the tire When the rotation angle belongs to a rotation angle range in which the strength of the request signal is increased, the signal strength of the request signal is set to a weak level, and the rotation angle of the tire is a rotation angle range in which the strength of the request signal is decreased. And a setting unit that sets the signal strength of the request signal to a strong level.

  In this aspect, when the rotation angle of the tire belongs to a rotation angle range in which the request signal reaching the detection device is strong, the setting unit sets the signal strength of the request signal to a weak level. Conversely, when the rotation angle of the tire belongs to a rotation angle range in which the request signal reaching the detection device is weak, the setting unit sets the signal strength of the request signal to a high level. Therefore, even if the reception sensitivity of the request signal in the detection device is not set high, the detection device can receive the request signal and can transmit the air pressure signal to the monitoring device in response to the request of the monitoring device.

(3) The request signal transmission unit transmits setting information for setting the signal strength of the air pressure signal according to the angle information acquired by the acquisition unit together with the request signal, and the air pressure signal The transmission unit preferably transmits the air pressure signal at a signal intensity corresponding to the setting information received together with the request signal.

  In this aspect, the detection device transmits an air pressure signal to the monitoring device with a signal intensity corresponding to the rotation angle of the tire. The positional relationship between the monitoring device and the detection device changes depending on the rotation angle of the tire when the vehicle is stopped, and the intensity of the air pressure signal reaching the monitoring device also changes. However, since the detection device can change the signal strength of the air pressure signal according to the rotation angle of the tire, the monitoring device can receive the air pressure signal of a certain strength or more regardless of the rotation angle of the tire. Become. Therefore, the detection device can set the signal strength of the air pressure signal as high as necessary, and the power consumption in the detection device can be suppressed.

(4) The monitoring device determines a rotation angle range in which the strength of the pneumatic signal reaching the monitoring device is increased according to a rotation angle of the tire, and a rotation angle range in which the strength of the request signal is decreased, and An air pressure signal setting information storage unit that stores information for setting the signal strength of the air pressure signal is provided, and the request signal transmission unit stores the angle information acquired by the acquisition unit and the air pressure signal setting information storage unit. Based on the information, when the rotation angle of the tire belongs to a rotation angle range in which the strength of the air pressure signal is increased, setting information for setting the signal strength of the air pressure signal to a weak level is transmitted, and the tire When the rotation angle belongs to a rotation angle range in which the strength of the air pressure signal is weakened, the setting information for setting the signal strength of the air pressure signal to a high level is transmitted. It is preferred.

  In this aspect, when the rotation angle of the tire belongs to a rotation angle range in which the air pressure signal reaching the monitoring device is strong, the detection device transmits the air pressure signal at a weak level. On the contrary, when the rotation angle of the tire belongs to the rotation angle range in which the request signal reaching the monitoring device is weak, the detection device and the air pressure signal are transmitted at a high level. Therefore, the detection device can set the signal strength of the air pressure signal as high as necessary, and the power consumption in the detection device can be suppressed.

(5) A monitoring device according to this aspect is provided in a tire of a vehicle, and receives the air pressure signal transmitted from a detection device that wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire. A monitoring device that monitors tire air pressure, and obtains the air pressure signal with an acquisition unit that acquires angle information indicating a rotation angle of the tire, and a signal intensity corresponding to the angle information acquired by the acquisition unit. A request signal transmission unit that wirelessly transmits the request signal to the detection device.

  In this aspect, similarly to aspect (1), the request signal can be received without setting the reception sensitivity of the request signal in the detection apparatus high, and the power consumption in the detection apparatus can be suppressed.

(6) A detection device according to this aspect is a detection device that is provided in a tire of a vehicle and wirelessly transmits a pneumatic signal obtained by detecting the pneumatic pressure of the tire, and a request signal that requests the pneumatic signal And a request signal receiving unit that receives setting information for setting the signal strength of the air pressure signal according to the rotation angle of the tire, and when the request signal and the setting information are received by the request signal receiving unit, An air pressure signal transmitting unit that transmits the air pressure signal at a signal intensity corresponding to the setting information.

  In this aspect, like the aspect (3), the detection device can set the signal intensity of the air pressure signal as high as necessary, and the power consumption in the detection device can be suppressed.

[Details of the embodiment of the present invention]
A specific example of a tire pressure monitoring system according to an embodiment of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

  FIG. 1 is a conceptual diagram showing a configuration example of a tire pressure monitoring system according to an embodiment of the present invention. The tire pressure monitoring system according to the present embodiment includes a monitoring device 1 provided at an appropriate position of the vehicle body, a detection device 2 provided on each of the wheels of a plurality of tires 3 attached to the vehicle C, and a notification device 4. The wheel speed sensor 5 is provided. In the tire pressure monitoring system of the present embodiment, when the vehicle stops, the monitoring device 1 performs two-way wireless communication with each detection device 2 to acquire the pressure information of each tire 3, and the notification device 4 acquires the acquired pressure information. Notification according to is performed.

  A plurality of LF transmission antennas 14 a corresponding to the respective tires 3 are connected to the monitoring device 1. For example, the four LF transmitting antennas 14a are provided at the right front, right rear, left rear, and left front tire positions of the vehicle C. The tire position is a position around the tire house and its surroundings, and is a position where the detection device 2 provided in each tire 3 can individually receive a signal transmitted from each LF transmission antenna 14a.

  Note that the LF band and the UHF band are examples of a radio wave band used when performing wireless communication, and are not necessarily limited thereto. The monitoring device 1 is connected to the notification device 4 via a communication line, and the monitoring device 1 transmits the acquired air pressure information to the notification device 4. The notification device 4 receives the air pressure information transmitted from the monitoring device 1 and notifies the air pressure of each tire 3. Further, the notification device 4 issues a warning when the air pressure of the tire 3 is less than a predetermined threshold value.

  FIG. 2 is a block diagram illustrating a configuration example of the monitoring device 1. The monitoring device 1 includes a control unit 11 that controls the operation of each component of the monitoring device 1. A storage unit 12, a pneumatic signal reception unit 13, a request signal transmission unit 14, a communication unit 15, and an acquisition unit 16 are connected to the control unit 11.

  The control unit 11 is a microcomputer having, for example, one or a plurality of CPUs (Central Processing Units), a multi-core CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. The CPU of the control unit 11 is connected to the storage unit 12, the pneumatic signal reception unit 13, the request signal transmission unit 14, the communication unit 15, and the acquisition unit 16 via an input / output interface. The control unit 11 controls the operation of each component by executing a control program stored in the storage unit 12 and executes the tire pressure monitoring process according to the present embodiment.

  The storage unit 12 is a nonvolatile memory such as an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. The storage unit 12 stores a control program for executing tire pressure monitoring processing by the control unit 11 controlling the operation of each component of the monitoring device 1. The storage unit 12 also stores an identifier table 12a, an LF dead zone table 12b, and an RF dead zone table 12c. Details of each table will be described later.

  An RF receiving antenna 13 a is connected to the air pressure signal receiving unit 13. The air pressure signal receiving unit 13 receives a signal transmitted from the detection device 2 using radio waves in the RF band by the RF receiving antenna 13a. The air pressure signal receiving unit 13 is a circuit that demodulates the received signal and outputs the demodulated signal to the control unit 11. Although a UHF band of 300 MHz to 3 GHz is used as a carrier wave, the carrier wave is not limited to this frequency band.

The request signal transmission unit 14 is a circuit that modulates the signal output from the control unit 11 into an LF band signal and transmits the modulated signal to the plurality of detection devices 2 from the plurality of LF transmission antennas 14a. Specifically, the request signal transmission unit 14 sequentially transmits a request signal for requesting transmission of a pneumatic signal from each LF transmission antenna 14a in accordance with the control of the control unit 11. As a carrier wave, an LF band of 30 kHz to 300 kHz is used, but it is not limited to this frequency band.
Further, the request signal transmission unit 14 includes an LF signal strength changing unit 14b that changes the signal level of the request signal to be transmitted. The LF signal strength changing unit 14 b is an amplifier, for example, and changes the signal strength of the request signal according to the control signal output from the control unit 11.

  The communication unit 15 is a communication circuit that performs communication according to a communication protocol such as CAN (Controller Area Network) or LIN (Local Interconnect Network), and is connected to the notification device 4. The communication unit 15 transmits information related to the air pressure of the tire 3 to the notification device 4 under the control of the control unit 11.

  The notification device 4 is, for example, a display unit or a display unit provided in an instrument panel instrument, which is provided with a display unit or a speaker that notifies information related to the air pressure of the tire 3 transmitted from the communication unit 15 by an image or sound. Etc. The display unit is a liquid crystal display, an organic EL display, a head-up display, or the like. For example, the notification device 4 displays the air pressure of each tire 3 provided in the vehicle C with images or characters.

A plurality of wheel speed sensors 5 that detect the rotational speed of each tire 3 are connected to the acquisition unit 16. The wheel speed sensor 5 is, for example, a pulse encoder provided on the vehicle body side, and outputs one pulse signal each time the tire 3 rotates by a predetermined angle. For this reason, when the tire 3 rotates once, a predetermined number of pulse signals are output from the wheel speed sensor 5. The acquisition unit 16 can detect the rotation angle of the tire 3 by counting the pulse signals output from the wheel speed sensor 5. For example, an arbitrary position is set as the origin (0 degree) (see FIG. 4), and the rotation angle of the tire 3 rotated with reference to the origin can be detected from the number of pulse signals output from the wheel speed sensor 5. . The position of the origin is not particularly limited, but is, for example, a rotation angle at which the signal strength of the air pressure signal received by the monitoring device 1 is maximized. The acquisition unit 16 counts the number of pulses output from the wheel speed sensor 5 for each of the plurality of wheel speed sensors 5 corresponding to each tire 3, and the counting result, that is, an angle indicating the rotation angle of each tire 3. Information is output to the control unit 11. Note that the pulse signal counted by the acquisition unit 16 is reset when the tire 3 rotates once. Further, the wheel speed sensor 5 can detect the rotation direction of the tire 3, and when the tire 3 is rotating in the forward direction, the number of pulses is added, and when the tire 3 is rotating in the reverse direction, Subtract the number of pulses.
If the tire 3 is removed, the origin position may be shifted. That is, the correspondence between the count value of the pulse signal and the rotation angle of the tire 3 may change. Therefore, the monitoring device 1 may correct the origin as appropriate. For example, the received signal strength of a pneumatic signal received when the vehicle C moves and the tire 3 rotates is detected by a received signal strength sensor (not shown), and a pulse signal is counted to receive the pneumatic signal. The origin may be corrected by setting the count value of the pulse signal when the signal intensity is maximum to 0. Such an origin correction method is an example, and is not particularly limited.

  FIG. 3 is a conceptual diagram showing an example of the identifier table 12a. The identifier table 12a includes a plurality of tire positions, an antenna identifier for identifying the LF transmission antenna 14a disposed in the vicinity of the tire position, and a sensor identifier of the detection device 2 provided in the tire 3 at the tire position. It is stored in association. In the example shown in FIG. 3, the antenna identifiers “1”, “2”, “3”, and “4” are the LF transmission antennas provided at the right front, right rear, left front, and left rear tire positions, respectively. 14a is shown. Also, sensor identifiers “1111”, “2222”, “3333”, and “4444” are associated with the front right, right rear, left rear, and left front tire positions, respectively.

  4 is a conceptual diagram showing an LF dead zone, and FIG. 5 is a conceptual diagram showing an example of an LF dead zone table. Since the detection device 2 is provided on the wheel of the tire 3, when the tire 3 rotates, the positional relationship between the LF transmission antenna 14a and the detection device 2 changes. For this reason, as shown in FIG. 4, there is a rotation angle range in which the intensity of the request signal reaching the detection device 2 becomes weak. The said angle range is an area | region where the detection apparatus 2 cannot receive the request signal transmitted with the weak signal strength from the monitoring apparatus 1, or it becomes difficult to receive. Hereinafter, the region is appropriately referred to as an LF dead zone.

  The LF dead zone table 12b associates and stores a plurality of tire positions and a rotation angle range in which the intensity of the LF signal reaching the detection device 2 provided on the tire 3 at the tire position becomes weak. The rotation angle range in which the intensity of the LF signal is weak is a value obtained by measurement in advance. The rotation angle range represents, for example, the rotation angle with the origin as 0 expressed by the number of pulses. The LF dead zone table 12b corresponds to the request signal setting information storage unit of the above aspect.

FIG. 6 is a conceptual diagram showing an example of the RF dead zone table 12c. Similar to the request signal, there is a rotation angle range in which the intensity of the air pressure signal reaching the monitoring device 1 becomes weak. The angle range is an area where the monitoring device 1 cannot receive the air pressure signal transmitted from the detection device 2 with a weak signal strength, or is difficult to receive. Hereinafter, the region is appropriately referred to as an RF dead zone.
The RF dead zone table 12c associates a plurality of tire positions with a rotation angle range in which the intensity of the RF signal transmitted from the detection device 2 provided on the tire 3 at the tire position and reaching the monitoring device 1 is weakened. I remember it. The rotation angle range in which the RF signal cannot be received is a value obtained by measurement in advance. The rotation angle range represents, for example, the rotation angle with the origin as 0 expressed by the number of pulses. Note that the rotation angle range in which the strength of the request signal reaching the detection device 2 is weak and the rotation angle range in which the strength of the air pressure signal reaching the monitoring device 1 is generally different. Further, each angle range is different for each tire 3. The RF dead zone table 12c corresponds to the air pressure signal setting information storage unit of the above aspect.

  FIG. 7 is a block diagram illustrating a configuration example of the detection device 2. The detection device 2 includes a sensor control unit 21 that controls the operation of each component of the detection device 2. A sensor storage unit 22, an air pressure signal transmission unit 23, a request signal reception unit 24, an air pressure detection unit 25 and a temperature detection unit 26 are connected to the sensor control unit 21.

  The sensor control unit 21 is a microcomputer having, for example, one or a plurality of CPUs, a multi-core CPU, a ROM, a RAM, an input / output interface, and the like. The CPU of the sensor control unit 21 is connected to the sensor storage unit 22, the air pressure signal transmission unit 23, the request signal reception unit 24, the air pressure detection unit 25, and the temperature detection unit 26 via an input / output interface. The sensor control unit 21 reads a control program stored in the sensor storage unit 22 and controls each unit. The detection device 2 includes a battery (not shown) and operates with electric power from the battery.

  The sensor storage unit 22 is a nonvolatile memory. The sensor storage unit 22 stores a control program for the CPU of the sensor control unit 21 to perform processing related to detection and transmission of the air pressure of the tire 3. Further, a unique sensor identifier for identifying itself and the other detection device 2 is stored.

  The air pressure detection unit 25 includes, for example, a diaphragm, and detects the air pressure of the tire 3 based on the deformation amount of the diaphragm that changes depending on the magnitude of the pressure. The air pressure detection unit 25 outputs a signal indicating the detected air pressure of the tire 3 to the sensor control unit 21.

  The temperature detection unit 26 includes, for example, an element whose electrical resistance changes with temperature, and detects the temperature of the tire 3 based on the voltage between the elements that changes with temperature change. The temperature detection unit 26 outputs a signal indicating the detected temperature of the tire 3 to the sensor control unit 21.

  An RF transmission antenna 23 a is connected to the air pressure signal transmission unit 23. The air pressure signal transmission unit 23 modulates the air pressure signal generated by the sensor control unit 21 into a UHF band signal, and transmits the modulated air pressure signal using the RF transmission antenna 23a. The air pressure signal transmission unit 23 includes an RF signal strength changing unit 23b that changes the signal level of the air pressure signal to be transmitted. The RF signal strength changing unit 23 b is an amplifier, for example, and changes the signal strength of the pneumatic signal according to the control signal output from the sensor control unit 21.

  The request signal receiving unit 24 is connected to an LF receiving antenna 24a. The request signal receiving unit 24 receives various signals such as a request signal transmitted from the monitoring device 1 using radio waves in the LF band by the LF receiving antenna 24 a and outputs the received signals to the sensor control unit 21.

  The sensor control unit 21 executes the control program to acquire signals indicating the air pressure and temperature of the tire 3 from the air pressure detection unit 25 and the temperature detection unit 26, and the air pressure information and temperature information based on the signals and the detection device 2 is generated and output to the air pressure signal transmission unit 23.

  Next, the procedure of the tire pressure monitoring process will be described. Below, the process of the monitoring apparatus 1 and the process of the detection apparatus 2 are demonstrated separately.

  FIG. 8 is a flowchart showing a processing procedure of the monitoring apparatus 1. The control unit 11 of the monitoring device 1 monitors the air pressure of the tire 3 by executing the following process at an arbitrary timing while the vehicle is stopped. For example, the following processing is executed at the timing when an ignition switch (not shown) is turned on from an off state. First, the control unit 11 selects a tire position where the air pressure of the tire 3 has not been detected among the right front, left front, right rear, and left rear (step S11).

  Next, the control unit 11 acquires angle information of the tire 3 related to the selected tire position from the acquisition unit 16 (step S12). And the control part 11 determines whether the detection apparatus 2 provided in the tire 3 exists in LF dead zone (step S13). Specifically, the control unit 11 reads out the rotation angle range of the LF dead zone corresponding to the selected tire position from the LF dead zone table 12b, and determines whether or not the rotation angle of the tire 3 belongs to the rotation angle range. To do.

  When it is determined that the detection device 2 is in the LF dead zone (step S13: YES), the control unit 11 outputs a control signal to the LF signal strength changing unit 14b to set the signal strength of the LF signal to a strong level (step). S14) When it is determined that the detection device 2 is not in the LF dead zone (step S13: NO), the control unit 11 outputs a control signal to the LF signal strength changing unit 14b to set the signal strength of the LF signal to a weak level. (Step S15).

  When the process of step S14 or step S15 is completed, the control unit 11 determines whether or not the detection device 2 provided on the tire 3 is in the RF dead zone (step S16). Specifically, the control unit 11 reads out the rotation angle range of the RF dead zone corresponding to the selected tire position from the RF dead zone table 12c, and determines whether or not the rotation angle of the tire 3 belongs to the rotation angle range. To do.

  If it is determined that the detection device 2 is in the RF dead zone (step S16: YES), the control unit 11 sends a request signal including setting information for setting the RF signal intensity in the detection device 2 to a strong level in step S11. Transmission is performed from the LF transmission antenna 14a corresponding to the selected tire position (step S17). When it is determined that the detection device 2 is not in the RF dead zone (step S16: NO), the control unit 11 sends a request signal including setting information for setting the RF signal intensity in the detection device 2 to a weak level in step S11. Transmission is performed from the LF transmission antenna 14a corresponding to the selected tire position (step S18).

  When the process of step S17 or step S18 is completed, the control unit 11 receives the air pressure signal transmitted from the detection device 2 in response to the request signal (step S19), and notifies the air pressure information included in the received air pressure signal. By outputting to the device 4, the driver is notified of air pressure information (step S20).

  Next, the control unit 11 determines whether or not all the air pressures of the tires 3 have been confirmed (step S21). If it is determined that there is a tire 3 whose air pressure has not been confirmed (step S21: NO), the control unit 11 returns the process to step S11, and executes the same process for the tire 3 whose air pressure has not been detected. When it determines with having confirmed the air pressure of all the tires 3 (step S21: YES), the control part 11 finishes a tire air pressure monitoring process.

  FIG. 9 is a flowchart showing a processing procedure of the detection apparatus 2. When the vehicle is stopped and the tire 3 is not rotating, the detection device 2 does not detect the air pressure and does not transmit the air pressure signal, and is in a standby state in which power consumption is reduced. The detection device 2 in the standby state monitors the request signal transmitted from the monitoring device 1, and executes the following process when receiving the request signal. The sensor control unit 21 of the detection device 2 is activated upon reception of the request signal (step S31). And the sensor control part 21 detects the air pressure and temperature of the tire 3 by the air pressure detection part 25 and the temperature detection part 26 (step S32). And the sensor control part 21 determines whether the setting information for setting RF signal intensity | strength to a strong level is contained in the request signal (step S33). When it is determined that the setting information for setting the RF signal intensity to the strong level is included (step S33: YES), the sensor control unit 21 outputs a control signal to the RF signal intensity changing unit 23b to output the RF signal. Is set to a high level (step S34), and it is determined that setting information for setting the RF signal strength to a weak level is included (step S33: NO), the sensor control unit 21 performs RF A control signal is output to the signal strength changing unit 23b to set the signal strength of the RF signal to a weak level (step S35).

  Next, the sensor control unit 21 generates an air pressure signal including the air pressure information and temperature information detected in step S32 and a sensor identifier unique to the own detection device 2, and the generated air pressure signal is RF-transmitted. Transmission is performed from the antenna 23a to the monitoring device 1 (step S36), and the process is terminated.

In the tire pressure monitoring system configured as described above, the monitoring device 1 and the detection device 2 can perform bidirectional communication without adjusting the rotation angle of the tire 3 when the vehicle is stopped. Power consumption can be reduced.
Specifically, the monitoring device 1 refers to the LF dead zone table 12b to determine whether or not the detection device 2 of each tire 3 is at a position where the signal intensity of the request signal reaching the detection device 2 is reduced. Can be determined. And the monitoring apparatus 1 sets the intensity | strength of LF signal to a strong level, when transmitting a request signal with respect to the detection apparatus 2 in the position where the signal intensity of a request signal falls. Therefore, even if the rotation angle of the tire 3 is not adjusted or the reception sensitivity of the LF signal in the detection device 2 is not set high, the monitoring device 1 can activate the detection device 2 and execute the air pressure detection process. The power consumption of the detection device 2 can be suppressed.

Further, the detection device 2 can transmit an air pressure signal to the monitoring device 1 with an RF signal intensity corresponding to the rotation angle of the tire 3.
Specifically, the monitoring device 1 refers to the RF dead zone table 12c, so that the detection device 2 of each tire 3 is transmitted from the detection device 2 and the signal intensity of the pneumatic signal reaching the monitoring device 1 is reduced. It can be determined whether or not it is in a position to be. Then, when the monitoring device 1 transmits a request signal to the detection device 2 at a position where the air pressure signal decreases, setting information for setting the RF signal strength to a high level is included.
Therefore, the monitoring device 1 can receive a high-level air pressure signal transmitted from the detection device 2 without adjusting the rotation angle of the tire 3 when the vehicle is stopped. In addition, when the monitoring device 1 transmits a request signal to the detection device 2 in a position where the signal strength of the air pressure signal does not decrease, setting information for setting the signal strength of the RF signal to a weak level is included. Therefore, it is possible to transmit an air pressure signal that can be received by the monitoring device 1 without constantly setting the RF signal intensity in the detection device 2 to a high level, and to suppress power consumption of the detection device 2.

DESCRIPTION OF SYMBOLS 1 Monitoring apparatus 2 Detection apparatus 3 Tire 4 Notification apparatus 5 Wheel speed sensor 11 Control part 12 Storage part 12a Identifier table 12b LF dead zone table 12c RF dead zone table 13 Air pressure signal receiving part 13a RF receiving antenna 14 Request signal transmitting part 14a LF transmitting antenna 14b LF signal strength change unit 15 communication unit 16 acquisition unit 21 sensor control unit 22 sensor storage unit 23 air pressure signal transmission unit 23a RF transmission antenna 23b RF signal strength change unit 24 request signal reception unit 24a LF reception antenna 25 air pressure detection unit 26 Temperature detector C Vehicle

Claims (6)

A detection device that is provided on a tire of a vehicle and wirelessly transmits a pneumatic signal obtained by detecting the pressure of the tire, and receives the pneumatic signal transmitted from the detection device and monitors the pneumatic pressure of the tire A tire pressure monitoring system comprising a monitoring device,
The monitoring device
An acquisition unit for acquiring angle information indicating a rotation angle of the tire;
A request signal transmission unit that wirelessly transmits a request signal for requesting the air pressure signal to the detection device with a signal intensity corresponding to the angle information acquired by the acquisition unit,
The detection device includes:
A request signal receiving unit for receiving the request signal transmitted from the monitoring device;
A tire pressure monitoring system comprising: a pneumatic signal transmission unit that transmits the pneumatic pressure signal when the request signal is received by the request signal receiving unit. The monitoring device
The signal strength of the request signal is set by discriminating a rotation angle range in which the intensity of the request signal reaching the detection device is increased according to a rotation angle of the tire and a rotation angle range in which the intensity of the request signal is decreased. A request signal setting information storage unit for storing information for,
Based on the angle information acquired by the acquisition unit and the information stored in the request signal setting information storage unit, when the rotation angle of the tire belongs to a rotation angle range in which the strength of the request signal is increased, the request signal A setting unit configured to set the signal strength of the request signal to a high level when the tire rotation angle belongs to a rotation angle range in which the strength of the request signal is weakened. Item 2. The tire pressure monitoring system according to Item 1. The request signal transmitter is
Setting information for setting the signal strength of the air pressure signal according to the angle information acquired by the acquisition unit is transmitted together with the request signal;
The air pressure signal transmitter
The tire pressure monitoring system according to claim 1 or 2, wherein the tire pressure signal is transmitted at a signal strength corresponding to the setting information received together with the request signal. The monitoring device
The signal strength of the air pressure signal is set by discriminating the rotation angle range in which the strength of the air pressure signal reaching the monitoring device is increased according to the tire rotation angle and the rotation angle range in which the strength of the request signal is weakened. A pneumatic signal setting information storage unit for storing information for
The request signal transmitter is
Based on the angle information acquired by the acquisition unit and the information stored in the air pressure signal setting information storage unit, when the rotation angle of the tire belongs to a rotation angle range in which the intensity of the air pressure signal is increased, the air pressure signal When setting information for setting the signal strength of the tire to a weak level is transmitted and the rotation angle of the tire belongs to a rotation angle range in which the strength of the air pressure signal becomes weak, the signal strength of the air pressure signal is set to a high level. The tire pressure monitoring system according to claim 3, wherein setting information for transmitting is transmitted. A monitoring device that is provided in a tire of a vehicle and that receives the air pressure signal transmitted from a detection device that wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire and monitors the air pressure of the tire. ,
An acquisition unit for acquiring angle information indicating a rotation angle of the tire;
A monitoring apparatus comprising: a request signal transmission unit that wirelessly transmits a request signal for requesting the air pressure signal to the detection device with a signal intensity corresponding to the angle information acquired by the acquisition unit. A detection device that is provided on a tire of a vehicle and wirelessly transmits an air pressure signal obtained by detecting the air pressure of the tire,
A request signal receiving unit for receiving a request signal for requesting the air pressure signal and setting information for setting a signal strength of the air pressure signal according to a rotation angle of the tire;
A detection apparatus comprising: a pneumatic signal transmission unit configured to transmit the pneumatic signal at a signal intensity corresponding to the setting information when the request signal reception unit receives the request signal and the setting information.

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